Recliner chairs and other reclining seating units have proven to be popular with consumers. These seating units typically move from an upright position, in which the backrest is generally upright, to one or more reclined positions, in which the backrest pivots to be less upright. The movement of the seating unit between the upright and reclined positions is typically controlled by a pair of matching reclining mechanisms that are attached to the seat, backrest and base of the chair.
One particularly popular reclining chair is the so-called "rocker-recliner," which can, when in the upright position, rock with a forward and rearward motion similar to that of a traditional rocking chair. A typical rocker recliner, one of which is illustrated in U.S. Pat. No. 4,519,647 to Rogers, includes a wooden arcuate rocker cam that is attached with the lower portion of each mechanism, with the lower convex surface of the rocker cam contacting a level portion of the base (also typically formed of wood). Also, a spring assembly is mounted to the base of the chair and to each rocker cam. Each spring assembly includes two quite stiff, vertically-oriented helical springs attached to mounting brackets that are in turn fixed to the base and to the rocker cam. When the chair is in its upright position and is unoccupied, the seat, backrest and reclining mechanisms reside above the base, the rocker springs are deflected only along their longitudinal axes, and the rocker cams rest on a level portion of the base. When an occupant sits on the chair and applies a forwardly- or rearwardly-directed force to the seat or backrest, the seat and backrest move relative to the base. The path of movement is defined by the convex shape of the rocker cams as they rock on the level surface of the base, with the result that the seat and backrest simulate the rocking motion of a rocking chair. During the rocking movement, the rocker springs deflect such that their top portions bend away from their longitudinal axes as the chair rocks forward and back. The deflection in the springs urges the springs (and, in turn, the seat and backrest) to return to their original positions as the chair returns to and through the upright position. In this manner, the chair is capable of providing a controlled rocking motion when in the upright position. Most, if not all, chairs of this design include some type of safety feature, such as an extendable foot, that prevents rocking when the chair is in a reclined position.
One specific concern raised by the typical rocker-recliner mechanism is the production of the rocker cams. Clearly, the rocking motion of the chair is controlled by the shape and condition of the arcuate surfaces of the rocker cams. Thus, incorrectly shaped rocker cams can preclude a smooth rocking motion. Also, imperfections in the rocker cam surface, such as nicks or bumps, can often be felt by the occupant during rocking. As such, production of wooden rocker cams can be quite precise and labor-intensive, which can raise their cost significantly.
Because of their rocking capabilities, rocker-recliners of the configuration described above have achieved significant popularity, and as such are in demand in many different aesthetic styles and reclining motions. For example, some chairs are constructed so that the seat and backrest are fixed relative to one another and recline as a unit, while others are designed so that the backrest can pivot relative to the seat. Some recliners move to only one reclined position, while others move to two reclined positions. Of course, these varied motions are controlled by the reclining mechanisms, each of which must be configured differently to operate as desired. In addition, the aesthetic diversity demanded by consumers can also impose significant constraints on chair designers as they attempt to design a chair that operates properly and is visually appealing.
Due to the complexity of reclining mechanisms, manufacturers of recliner chairs have attempted to limit the number of different mechanisms they produce. The same is true of rocker cams and rocker spring assemblies. As such, designers are forced to devise configurations mechanisms, rocker cams, springs and bases that represent compromises between style and operational concerns. In addition, combining a number of different mechanisms, rocker cams, springs, bases, and seat and backrest styles can also raise manufacturing concerns.
One proposed alternative to the typical rocker-recliner mechanism is a rocker unit, available from Super Sagless, Tupelo, Miss., that incorporates the rocker springs and the base as a single unit. The base is a single welded piece comprising two spaced-apart legs and two cross beams welded to and connecting the legs. Thermoplastic rocker cams rest on the upper surfaces of the base legs. Each of these is positioned beneath and mounted to an auxiliary mounting plate. The auxiliary mounting plates are welded to two additional cross members that are positioned above the base cross members. The rocker spring assemblies are mounted between the cross members of the base and the cross members attached to the auxiliary mounting plates. A rocker unit of this configuration can be assembled in one location, then shipped to another manufacturing site, where reclining mechanisms can be attached to each auxiliary mounting plate and mounted thereto during production of a chair.
Although under some circumstances there is some advantage to the use of this single unit, there are significant shortcomings. For example, replacement of a faulty rocker cam can be laborious, as the cross members welded to the auxiliary mounting plates must be disassembled from the rocker springs in order to enable the rocker cams to be removed from the auxiliary mounting plates. Also, the rocker unit is rather bulky, therefore rendering it cumbersome to ship and store. In addition, the unit does not permit the adjustment of the positions of the rocker springs relative to the rocker cams and the reclining mechanisms after assembly, so its usefulness with a wide variety of mechanisms may be limited. Further, the available space for attaching the auxiliary mounting plates to a mounting plate of an existing reclining mechanism is limited, in particular by the presence of the cross members of the auxiliary mounting plates.